The present invention relates to a foamable biocidal composition.
The chemical control of bacteria and viruses is assuming increasing importance in the hosiptal and medical environment. Outbreaks of infections such as Methyicylin resistant Staph Aureus are causing illness, death and even temporary closure of wards in some hospitals.
This situation has been exacerbated by the failure of many bacteria to respond to conventional antibiotics. Accordingly, the need for effective control of bacterial and virus organisms is assuming greatly increased significance.
In the case of hand and skin disinfection a biocidal agent needs to kill the widest possible range of microorganisms in the least possible time without toxicity, irritation or other hazard and have a long shelf life.
Typical of these biocides are chlorine, iodophors and organic chemicals such as chlorhexidine which are commonly employed in hospitals and surgeries. The most widely accepted form of safe, effective biocide is a solution of chlorhexidine gluconate in aqueous ethanol. A full discussion of this product appears in the paper entitled "Detergents compared with each other and with antiseptics as skin `degerminating agents`" by H. A. Lily et al in Journal of Hygiene (U.K.). Further technical disclosure of the product appears in Australian Pat. Nos. 157,758 and 222,033. Conventionally, this chlorhexidine solution is commercially supplied in a pump pack or manufactured by the hospital pharmacist as required.
Unfortunately, however, in use known alcohol and chlorhexidine solutions have inherent difficulties including the following:
(1) Openable bottles of alcoholic chlorhexidine are subject to contamination both at the time of fitting the pump head and when the pump is being operated.
(2) The 60-70% aqueous ethanol system is highly flammable. Spillage from the plastic bottle or dispenser at any time could result in a fire.
(3) The mist as applied from pump dispensers is a highly flammable mist. This could be highly dangerous since it is being sprayed directly onto the skin.
(4) The spray mist does not confine itself to the target area, wastage occurs due to overspray.
(5) The alcoholic lotion as sprayed on the skin is difficult to control due to its low viscosity. It tends to run off the skin and evaporate rapidly before being evenly distributed.
(6) The shelf life of pump packs of a volatile fluid such as alcohol is restricted by the fact that the pack is not sealed perfectly and evaporation can occur over a period of time.
(7) The spray or lotion product is messy to use since once one hand has been sprayed it must become contaminated as the pack is held to spray the other hand.
Accordingly, chlorhexidine alcohol solutions must be formulated very carefully to optimize its biocidal performance.
A foamable composition using aqueous chlorhexidine solutions is disclosed in U.S. Defensive publication T943,010. The composition generally utilizes chlorhexidene with more than 50% water at least 10% of ethoxylated alcohols surfactants with thickeners and propellants to form an aerosol foam similar to shaving cream foams.